The objectives of the proposed research are to develop mathematical models of blood flow, aggregation and hemolysis. Each red blood cell is considered as a deformable particle consisting of a flexible membrane filled with a viscous fluid. The model of the membrane developed previously is stiff with respect to changes in area, but readily deformed at constant area. The aggregation and disaggregation of the red blood cells will be studied by adding the electrostatic repulsion and binding forces of large molecules to the basic membrane model. Hemolysis will be studied by developing criteria for rupture based on the stresses and strains in the red blood cell membranes and comparing to experimental results for verification. Red blood cells will be considered in an infinite shear flow, near a rigid boundary and adhering to a boundary. The methods to be used are a variational principle for slow viscous flow containing elastic particles, a numerical technique (finite element method) and a statistical integration to derive suspension properties from one and two particle solutions. The results to be computed are the macroscopic viscometric behavior of blood, the individual red blood cell deformations and the details of the flow near a wall. An attempt will be made to simulate the Fahraeus-Lindgvist effect by integration over these solutions.